1. Field of the Invention
The present invention relates to an electronic control apparatus used in an electric power steering system for providing an assist force to a steering system of a vehicle by means of the rotational force of an electric motor.
2. Description of the Related Art
In the past, an electronic control apparatus described in a patent document (for example, Japanese patent No. 3644835) includes a power board on which a bridge circuit comprising semiconductor switching elements are mounted for switching a current supplied to an electric motor, a housing with conductive plates, etc., insert molded into an insulating resin and having high current parts mounted thereon, a control board having low current parts such as a microcomputer, etc., mounted thereon, a connecting member for electrically connecting the power board, the housing and the control board to one another, and a heat sink.
In the electronic control apparatus thus structured, the power board on which the semiconductor switching elements are mounted is required.
Although the connecting member is fixedly secured to the power board so as not to float at the time of soldering, an impact force generated when the connecting member is fixed onto the power board is transmitted to component parts such as the semiconductor elements on the power board before soldering thereof, so there occur positional shifts of such component parts.
As a result, there is the following problem. That is, the number of parts required increases, thus making the size of the electronic control apparatus larger and the production cost thereof higher, and the reliability of soldered joints of the parts mounted on the power board is reduced.